I2C Fails to Initialize when board is battery powered

Official Hardware MKR Family MKR WAN 1310
1

I2C locks up/hangs when powering the MKR WAN 1310 with a 3.7v 850mAh LiPo battery.

I have a Bosch BME688 sensor connected via the additional I2C port (5-pin connector with 1.0 mm pitch).

After uploading a sketch, the sensor initializes when the board is powered via the USB cable, but fails to do so when the battery is connected. I've included an errLeds() function that flashes the onboard LED to help debug, which helped me catch the fact that it's hanging.

Here is my code:

#include <MKRWAN.h>
#include <Adafruit_Sensor.h>
#include <Adafruit_BME680.h>
#include <ArduinoLowPower.h>
#include <Wire.h>
#include <LoRa.h>
...
void setup() {
  pinMode(LED_BUILTIN, OUTPUT);
  
  Serial.begin(115200);
  delay(1000);

  Wire.begin();

  if (!bme.begin(0x76)) {
    Serial.println("Could not find a valid BME680 sensor, check wiring!");
    errLeds();
    while (1)
      ;
  }

  initLoRaWan();

  LowPower.attachInterruptWakeup(RTC_ALARM_WAKEUP, dummy, CHANGE);
}
2

bigger batt needed..

Supported Batteries 	rechargeable Li-Ion, or Li-Po, 1024 mAh minimum capacity

good luck.. ~q

1 Like
3

Post an annotated schematic showing exactly how you have wired it. Also you need to watch a few tutorials on basic electronics. Arduinos have a love/hate relationship with volts/amps. Get them wrong they will not work to fry themselves. Get them correct and they will run for many years.

5

Upon further testing, I've concluded in this specific case it was not the battery that was giving me an issue. I am using a 2000mAh LiPo battery now for the record.

I was using a STEMMA/5 pin connector to connect my BME688 sensor to my board, and for some reason that connection was not getting power when the board is battery powered.

I instead used jumper cables to connect the sensor to Gnd, VCC, SCL, and SLA pins and THAT WORKS.

Does anyone know the logic behind this? I could not find any reason in the datasheet.

1 Like
6

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